The field of the invention relates to the creation of optical fiber couplers. More specifically, the invention relates to a motorized device for creating an optical fiber coupler with the amount of twist necessary to create a desired polarization state.
Fiber optic couplers are used to combine a light signal from two separate fibers into a single fiber. Additionally, couplers can divide a light signal from a single fiber to separate signals for separate fibers. If the coupler is made properly, the coupler should have little loss and back reflection. The goal when making a coupler is to produce a coupler that can transmit a good waveform. An example of a good waveform is shown in FIG. 1a. The insertion loss, or the distance between the signal and the zero axis on the graph, is minimal and the separation between signals is distinct. An example of a bad waveform is shown in FIG. 1b. The insertion loss is great and the signals are jumbled together.
One of the common methods used for creating a fiber optic coupler is called fused biconical tapering. In fused biconical tapering, the fibers are twisted, heated, and pulled. During tapering, the signal transmitted through the coupler resembles the waveform shown in FIG. 1c. After tapering, the waveform resembles the bad waveform of FIG. 1b. The coupler is twisted until a waveform approximating the one of FIG. 1a is achieved.
A difficulty arises in twisting the fibers in such a way as to create the desired wave form. The coupler needs to be twisted to create a waveform with the proper insertion loss, isolation of signals, and wavelength period. Currently an optic fiber is twisted using a manual twisting, mechanism. Manual twisting reduces precision and increases the likelihood of error.
A system and method for twisting together two fibers to create an optical fiber coupler is disclosed. In one embodiment, the two optic fibers are threaded through a chuck, which is rotated by a motor to create an amount of twist in the two optical fibers necessary to cause a light signal transmitted through the twisted fibers to have a desired wave form. A heater applies heat to the twisted fibers while rotating the chuck to create and optical fiber coupler.